At present, there are two kinds of paging modes in the CDMA system: a slotted mode and a non-slotted mode, wherein the non-slotted mode refers to a working mode that a mobile station monitors a forward-paging channel (F-PCH) continuously rather than monitors according to a designated slot.
Since the mobile station needs to perform demodulating and decoding to the F-PCH continuously, and to process the messages in the F-PCH, it will result in that the power in the battery is consumed very soon. In addition, under the circumstance that there is no any paging on the F-PCH, the system will broadcast a system parameter message periodically. For the mobile station which has obtained the parameters correctly and is in an idle state, to receive the parameters repeatedly is a kind of waste.
Therefore, in order to decrease the unnecessary monitoring of the mobile station to the F-PCH, and prolong the service time of the battery under the idle state, the slotted mode is provided in IS-95, this mode may correspond to the non-slotted mode. When working in the slotted mode, the mobile station under the idle state does not monitor the F-PCH continuously, but monitors the F-PCH at a designated time period at a certain interval according to a certain rule. The mobile station is in a sleep state in the intervals between every two times of F-PCH monitoring, i.e., the baseband processor and the radio frequency circuit reduce workload, or even stop working, therefore power consumption can be reduced.
In the slotted mode, the basic unit for dividing time is the slot of the F-PCH. The time length of one slot is 80 ms, i.e., four 20 ms paging channel frames. The mobile station in the slotted mode usually monitors the F-PCH once at a certain interval in the idle state. The time interval is called slot cycle, and the mobile station generally monitors one or two slots during one slot cycle. The slot cycle length which takes 1.28 s (=16×80 ms) as unit must be 1, 2, 4, 8, 16, 32, 64 or 128 times of 1.28 s. If T represents the slot cycle length, T=1.28×2i s, wherein i is a slot cycle index which can take the integral value from 0 to 7. The maximum value of the slot cycle may be 2048 slots, i.e., 163.84 s. Besides, a user may adjust the length of slot cycle expected by setting the slot cycle index of the station of his/her own wish. The slot cycle index after being adjusted is reported to the system through the messages of parameter change registration, originating call, paging response and so on.
In addition, the adjustment range of the user to the slot cycle is limited by current network configuration situation. In the system parameter message of the mobile station in the broadcast service area, there is a parameter, i.e., a max slot cycle index. This index stipulates the maximum slot cycle allowable to be used in current system. The slot cycle index actually used by the mobile station needs to be determined according to practical situation.
As mentioned above, in the slotted mode, the mobile station only monitors the paging at particular times, and generally only monitors one or two time period in the paging channel slot cycle, so that the power consumption of the mobile station is saved and the lifetime of the battery is prolonged. On the other hand, in the non-slotted working mode, the mobile station needs to monitor all the paging time periods.
In the trunking system, besides the parameters such as the slot cycle index in the original system, a push to talk (PTT) max slot cycle index is also introduced, which stipulates the parameters such as the maximum slot cycle index allowable to be used in current PTT system.
In addition, in the PTT system, there is a plurality of reasons resulting in the problem that it is slow to access for the mobile station being called after starting up, thus the functions such as PTT calling is limited. However, a technical scheme which can solve the problem has not been proposed yet.